Electric switch gear



June 22, 1937.

C. H. HILL ELECTRIC SWITCH GEAR Filed Jan. 8, 1956 Inventor: Charles H. Hill,

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Patented June 22, 1 937 UNITED STATES PATENT OFFICE Charles H. Hill, Drexel eral Electric York Hill, Pa., assignor to Gen- Company, a corporation of New Application January 8, 1936, Serial No. 58,029

Claims.

My invention relates to electric switch gear, more particularly to switch Contact structure, such as disconnect Contact structure, for electric switch gear of the drawout type.

In electric switch gear of the drawout type for example, wherein a circuit breaker unit is bodily movable to connected and disconnected positions with respect to stationary busbar structure, it is generally customary accurately .to aline the circuit breaker unit with respect to the coacting stationary portions of the circuit so that the coacting disconnect contacts engage within a very limited range of misalinement. Where plug and socket disconnect contact structure is used, as is often-the case, it will be apparent that the switch gear, must be quite accurately alined and that this requires very careful machining and fabrication of the structure, resulting in appreciably higher cost. The problem" of alinement is further complicated by the fact that in switch gear of the aforesaid type the disconnect contact structure must have a comparatively high normal current carrying capacity. Accordingly, it is highly desirable that the disconnect contacts maintain positive low resistance contact, notwithstanding appreciable misalinement of the coacting movable and stationary elements.

A principal object of my invention is the provision of improved relatively movable contact 0 structure which is effective to maintain comparatively high current carrying capacity notwithstanding appreciable misalinement of the relatively movable contact elements, and which is eflicient in operation and simple, rugged and 35 inexpensive in construction.

In accordance with my invention in one embodiment thereof, both of the relatively movable elements are provided with Contact surfaces,

preferably plane, which are interconnected in x 40 the closed circuit position'by a pair of contact members arranged in a scissors-like manner with respect to each other and mounted with respect to one of said elements. By reason of the flex-- ibility and automatic adjustment to forces either 5 in a generally transverse or longitudinal direction inherent in a scissors-like arrangement, accurate alinement, either lateral or angular, of the relatively movable switch gear elements is unnecessary within the limits of the contact area.

50 The disconnect switch overtravel or wipe, as

well as the desired Contact pressure, may be suitably provided for by resilient means, such ,as springs, interconnecting and biasing the contact members for scissors-like operation.

55 My invention will be more fully set forth'in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to 60 and forming a part of this specification.

Referring to the drawing, Fig. 1 is an elevational view of relatively movable portions of electric switch-gear of the drawouttype having disconnect contact structure embodying the present invention: Fig. 2 is an enlarged elevational view, partly in section, of the coacting disconnect contacts, and Fig. 3 is a plan view of the contacts shown by Fig. 2.

The drawout type switch gear shown by Fig.1 comprises a stationary structure I housing the stationary circuit connections, such as busbars (not shown), and a relatively movable switch gear unit 2 including a, circuit breaker 3. The terminals 3' of the circuit breaker are electrically connected to disconnect contacts, but one of which is shown at 4, for connecting the circuit breaker through coacting stationary disconnect contacts 5 to the busbar circuits. As illustrated, the switch gear is in the open circuit or isolated position, and to connect the circuit breaker to the busbars, the unit 2 is rolled towards the housing 1 so that the contacts 4. and 5 are in engagement. well known, further description thereof is believed unnecessary for a thorough understanding of the present invention.

Referring more particularly to Figs. 2 and 3 which illustrate in greater detail the disconnect switch contact structures 4 and 5, the relatively movable elements include insulating conductor bushings 6 and I for circuit terminating in contact plates 8 and 9 having opposing plane contact faces 8 and 9'. Suitably mounted with respect to one of the aforesaid elements, in the particular instance the stationary element, are a ,pair of contact members Ill and H 'co-pivotally mounted at l2 on a bracket support l3 which is mounted, as at I 4, on the conducting plate 9. The contact members l0 and H, which are generally of s shape, are arranged in a scissors-like mannerwith respect to each other and are suitably resiliently biased, such as by tension springs l5 and IS, in scissors closing movement, that is, so that one end of the member l0 and one end of member II are at all times biased into Contact engagement with the contact surface 9'. The opposite ends of the springs l5 and iii are anchored, such as by through-pins l5 and lfi'respectively, within depressions in the ends of the contact members.

The movable contact element may comprise simply the contact plate 8 arranged to move into direct butt engagement with the'corresponding ends of the members In and II. The pivot pin 12 interconnecting the contact members forms the scissors fulcrum and is movablefor limited transverse movement within the slot l2 formed in the bracket l3. With this arrangement, relative closing movement of the contact plates 8 and 9 within predetermined limits 'results simply This general type of switchgear-being in scissors opening movement of the members In and II, thereby tensioning the springs II and I6, and biasing the contact ends into engagement with the plane contact surfaces 8 and 8', respectively. The scissors pivot or fulcrum at H, as above pointed out, has a limited transverse movement within the slot II.

For the purpose of providing improved contact engagement between the members l0 and II and the coacting contact plates 8 and 8, the contact ends of the aforesaid scissors-like structure are formed as cylinders, or the equivalent thereof, at I! and I8, respectively, so as to make substantially line contact engagement with the coacting plane surfaces. That is, the contact is concentrated at a point of very high unit contact pressure. The contact engagement is further improved by providing the coacting contact surfaces at H and 20 with inserts or plating of good contact material, such as silver for example. The coacting contact surfaces at the plates 8 and 9 are shown as of appreciable area, in order to compensate for a considerable degree'of misalinement and to provide for the scissors-like wiping movement during the contact making and breaking operation. This also insures self-cleaning of the coacting contact surfaces.

It will be apparent from the above description that notwithstanding misalinement of the contact plates 8 and 9, either in a transverse or angular sense, the members Ill and H, by reason of the tension springs H5 and I, automatically adjust themselves to the coacting plane contact surfaces 8' and 8', respectively, so that high current carrying capacity is maintained.

The contact structure, while shown as including a definite scissors pivot or fulcrum, is obviously not limited to this particular arrangement, and it should be understoodv that by the term scissors-like as used herein, I intend to comprehend relatively movable members arranged generally in scissors or X fashion.

It should furthermore be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent in the United States is:

1. Electric switch contact structure comprising a pair of relatively movable elements, said elements provided with contact surfaces, a pair of contact members mounted with respect to each other in a scissors-like manner, means for mounting said contact members with respect to one of said elements, said contact members arranged to interconnect said elements so that in the closed circuit position of said contact structure the opposite ends of each member engage respectively the contact surfaces of said relatively movable elements, and means for biasing said contact members into contact engagement with said elements.

2. Electric switch contact structure comprising a pair of relatively movable elements, each element provided with a substantially plane contact surface, a pair of contact members mounted with respectto each other in a scissors-like manner arranged to interconnect said elements so that in the closed circuit position the opposite ends of each contact member engage respectively the plane contact surfaces of said relatively movable elements, means for mounting said contact members with respect to; one of said elements, and means resiliently biasing the aforesaid scissorslike contact arrangement so as to oppose scissors movement of said members after engagement of said contact structure.

3. Electric switch contact structure-comprising a pair of relatively movable elements, each of said elements provided with a substantially plane contact surface of appreciable area, a pair of contact members arranged in scissors-like manner between said contact surfaces, means mounting said scissors-like arrangement for limited movement with respect to one of said elements, and means resiliently biasing said scissors-like arrangement so as to increase the contact pressure between said scissors-like arrangement and said plane contact surfaces respectively and for automatically positioning said scissors-like arrangement with respect to said plane contact surfaces respectively for maintaining good contact relation therebetween.

4. Electric switch contact structure comprising a pair of relatively movable elements, each of said elements having a. contact surface, a pair of contact members arranged in scissors-lilac manner and pivotally mounted with respect toone of said elements, said scissors-like arrangement interconnecting said'contact surfaces in the closed circuit position and arranged so that the opposite ends of each contact member engage respectively the contact surfaces of-"said nelatively movable elements, said contact members having cylindrical shaped contact portions r at the contact ends thereof for engaging in substantially line contact the coacting contact surfaces, and means resiliently biasing saidmembers for scissors movement so that a contact portion of each of said contact members engages the contact surface of said one of said elements; the contact surface of the other of said elements engaging in the closed circuit position the contact portions at the other ends of said contact members, the contact surfaces of said elements being in good contact relation notwithstanding lateral or angular misalinement of said elements.

5. Electric switch contact structure comprising a pair of relatively movable elements, each of said elements having a contact surface of appreciable area, a pair of contact members arranged in scissors-like manner for interconnecting said contact surfaces in the closed circuit position, a pivot pin interconnecting said contact members forming the scissors fulcrum therefor, bracket structure mounted on one of said elements for supporting said scissors-like arrangement, said bracket structure having a slot within which said pivot pin is positioned for allowing bodily transverse movement of said scissors-like arrangement, and spring means interconnecting the ends of said contact members for biasing said ends into contact engagement with the contact surfaces respectively of said elements, scissors-like movement of said contact members in accordance with closing movement of saidelements flexing said spring means so that said elements are interconnected in good contact relation notwithstanding limited transverse and angular misalinement thereof.

CHARLES H. HIIL. 

